Other than Paul, no writer has had greater influence on the theology of justification than Augustine. This landmark study fills an astonishing lacuna in scholarship, offering the first comprehensive study of Augustine's theology of justification. Bringing an innovative approach to the topic, Christopher Mooney follows Augustine's own insistence that justification in Scripture is impossible to define apart from a precise understanding of faith. He argues that Augustine came to distinguish three distinct senses of faith, which are motivated by fear, hope, or love. These three types of faith result in very different accounts of justification. To demonstrate this insight, Mooney offers a developmental reading of Augustine, from his earliest to his latest writings, with special focus on the nature of justification, faith, hope, baptism, Augustine's reading of Paul, the Pelagian controversy, and Christology. Clear and engaging, Mooney's study of Augustine also illuminates numerous related issues, such as his theology of grace, the virtues, biblical exegesis, and the sacraments.